docs: RFC-18 operational runbook for flex-algo CLI workflows

[ben-malbeclabs]

Summary

Create an operational runbook documenting the RFC-18 flex-algo CLI workflows for use by the DZF team. This is distinct from the deployment runbook — it covers day-to-day operational tasks after flex-algo is live.

Motivation

The RFC-18 deployment surfaces a number of CLI workflows that aren't obviously discoverable: topology lifecycle, link tagging, tenant path assignment, unicast draining, and community stamping. A reference document makes these accessible without requiring RFC or code knowledge.

Scope

Each section should cover:

• Intent — what this workflow achieves and when to use it
• CLI commands — exact commands with --env devnet / --env mainnet-beta
• Expected output — what success looks like
• Known limitations — caveats, gotchas, or constraints

Proposed sections

1. Topology lifecycle — create, list, delete a TopologyInfo; initialize AdminGroupBits prerequisite via global-config set
2. Link topology assignment — tag/untag a link with a topology; use doublezero-admin migrate flex-algo for bulk backfill
3. Tenant path assignment — set include_topologies on a tenant to steer onto a non-default topology; clear back to UNICAST-DEFAULT
4. Unicast draining — set/clear unicast_drained on a link; effect on IS-IS flex-algo SPF; interaction with multicast (algo 0)
5. Community stamping — enable/disable via features.yaml (per-tenant, per-device, all); what gets stamped and what doesn't (multicast users excluded)
6. Flex-algo enable/disable — toggling features.yaml enabled flag via Ansible; what config is pushed and what is rolled back
7. Verification commands — show isis flex-algo, show running-config section administrative-group, controller log grep patterns

Related

• RFC: rfcs/rfc18-link-classification-flex-algo.md
• Deployment runbook: internal superpowers doc